VISIONS of a United States Congress living under term limits like that those Washington State is voting on tomorrow are only beginning to penetrate the Beltway."It's not believable yet," says Victor Kamber, a public relations and political consultant who works largely for labor unions and Democrats. He is trying, without success so far, to spark some organized national opposition to term limits. But while California, Oklahoma, and Colorado passed popular referendums for term limits last year, says Mr. Kamber, "it hasn't sunk into the Washington Beltway mentality that this is real." It's getting more real quickly. In 1992, 11 to 18 more states will vote on term limits, and many of them, like Washington, limit their federal representatives as well. One possible outcome of this popular movement is a constitutional amendment to limit US House and Senate terms to six or 12 consecutive years. Two visions are taking shape of what a term-limited Congress would look like. One is of a citizen legislature, made up of people never too remote from another life outside Washington. Without a career in Congress to look forward to, or a 10- to 12-year wait before holding any clout, politicians would be more assertive in putting together issue coalitions and taking short-term action. In this vision, Congress is peopled with more women, retirees, the self-employed, and people in vocations where public office is a good credential - much like in the remaining part-time state legislatures, notes Mark Petracca, a University of California at Irvine political scientist who has studied the term-limit concept. Most important to this happy view of term limits, attitudes of the members of Congress would change. Ideally, legislators would see their terms as a leave of absence from their work, says Ed Crane of the libertarian Cato Institute, rather than "clubby, docile" attitude he sees in the current Congress where even the best of people eventually get caught up in "that culture of ruling." The other vision foresees a term-limited Congress as a weaker body - full of unsophisticated short-termers unable to hold their own against the power of the president and the regulatory agencies. "The shorter [time] you're around, the less the executive [branch] has to worry about you," says Louis Fisher, a senior specialist in relations between branches of government at the Congressional Research Service. Without professionalism and knowledge developed over years of experience, Congress would be more dependent on the expertise of special-interest lobbyists and the members' own professional staffs. The change in attitudes envisioned here is that long-term outlooks and relationships will be replaced by short-term ambition. Norman Ornstein, Congress-watcher at the American Enterprise Institute, sees "no incentives to make short-term sacrifice for long-term gain."